The first aim of this study is the determination of the endogenous galactose, galactitol and galactonate pool sizes in the galactosemic patient, all of these being factors in the body galactose burden. The second aim is the determination of the in vivo galactose oxidation rate in the galactosemic patient. The third aim is the determination whether GALT activity can be modulated in vivo by pharmocologic administration of uridine, folate or progesterone.